Having statistical data in there provides support for my argument, it's better than having none. I don't see any problem with providing this data, considering I'm not using it as a primary inference to my conclusion.
I'd also like to know their (whoscored.com's) margin of error, their tracking method (assuming they are actually doing player tracking, which is the only way I can think of to collect the data that they have), and their error rate. Unfortunately, they provide none of those on their site.
If you have a better source or statistical data that proves Kovacic is more detrimental than useful as a DLP, in whatever method, perhaps by counting fingers or toes while watching, I'm happy to take them into account.